Lock.



No. 650,556. Patented May 29, I900. r r. FISCHER.

P LOCK.

(Application filed Feb. 16, 1900.,

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UNITE STATES PATENT FRIEDRICH risounn, on NEW YORK, N. Y.

LOCK.

SPECIFICATION forming part of Letters Patent No. 650,556, dated May 29, 1900.

Application filed February 16, 1900. Serial No. 5,427. (No model.)

To all whom it 11mg con/067 12 Be it known that I, FRIEDRICH FISCHER, a citizen of Germany, and a resident of New York city, county and State of New York, have invented certain new and useful Improvements in Locks, of which the following is a specification.

This invention relates to a lock the keyhole of which is protected by a pivoted guardplate which must be turned aside by means of an auxiliary key before the main key can be inserted and the room can be entered from the outside. Thus additional security against an unauthorized opening of the lock is pro vided. The guard-plate may be tightened over the keyhole by the occupant of the room, who may also turn it freely aside without the use of the auxiliary key.

In the accompanying drawings, Figure l is a side view of the lock with the cover removed and showing it open. Fig. 2 isa similar view showing it closed; Fig. 3, a cross-section on line 3 3, Fig. 1; Fig. at, a cross-section on line 4 4, Fig. 2; and Fig. 5, a face view of the keyplate.

The letter a represents the lock-case, having keyhole a and shown to be inserted within the mortise of a door b. Upon one face of the lock-case is rotatably mounted a guardplate 0, adapted to be projected over the keyhole or to be turned aside, so as to clear the same and permit the introduction of the key A. For the purpose of operating the plate 0 it is provided with a recess 0, adapted to be engaged by a small auxiliary key B, the keyplate d, Fig. 5, being provided with an additional keyhole d for the admission of this key. The guard-plate c is rigidly mounted upon a spindle e,passing transversely through the lock, Fig. 3, and provided within the lockcase with a lever e, influenced by a spring 6 that tends to normally project the plate 0 over the keyhole a.

The inner threaded end of the spindle e is engaged by the hollow internally-threaded shank f of aknob f, whichis accessible'from the interior of the apartment to be locked,

the parts e fthus constituting, jointly, a compound spindle which permits the free insertion of the look within the recess of the door.

The shank f is provided also with an external thread engaged by. a jam-nut g, which when tightened up against a plate (Z will draw the spindle e inward, and thus jam the plate 0 tightly against the lock-case a. 'To positively lock the plate 0 over the keyhole a when the plate is thus jammed, it may be provided with a small projection 0 that is adapted to enter the keyhole when the latter is closed.

The operation of the lock as thus far described is as follows: The nut 9 being slackened, the lock may be opened from the outside by bringing the auxiliary key B through keyhole d into engagement with the recess 0 of plate 0. By now turning the keyB the plate 0 is rotated, so as to clear the keyhole a, dotted lines, Fig. 2, and permit the insertion of the main key A, which may now be turned to operate the bolt. As soon as the key A has been introduced the key B is released, and'after the lock has been opened and the key A withdrawn the spring 6 will throw the guard-plate back into its original position over the keyhole. 7

If the occupant of the room desires to lock himself in in such a manner that the lock cannot possibly be opened even by one having the proper keys, he tightens the nut g up against the plate 01 and thereby draws the plate 0 firmly against the lock-case a over keyhole a. Thus the projection 0 will enter the keyhole, and the plate cannot possibly be swung aside by the key 13. If the occupant of the room wishes to leave and to lock the room from the outside without going to the trouble of using the key B, he opens the door, turns the plate 0 aside by knob f, and is thus free to insert the key A.

The locking mechanism may be of any suitable construction. It is shown to consist of a notched disk h, which is engaged by bit of key A and is pivota lly connected to the bolt 7;. A tumbler j holds the disk and bolt in their terminal positions. The drawings show the in vention applied to a latch-lock, the latch it being connected to disk It by links Z Z. WVhen the lock is closed, the link I releases the sleeve m of the latch-spindle, Fig. 2, and thus the latch cannot be manipulated as long as the bolt is shot out. When the bolt is drawn in, the link Z rengages sleeve m, Fig. 1, and the latch can be operated in the usual manner.

What I claim is 1.. In a lock, the combination'of a lock-case having a keyhole with a guard-plate adapted to be projected over the keyhole, a key for operating the guard-plate from one side of the lock, and means for operating the guard-plate from the other side of the lock, substantially as specified.

2. In a lock, the combination of a lock-case with a guard-plate adapted to be projected over the keyhole, a spindle upon which the guard-plate is mounted, a key for operating the guard-plate from one side of the lock, and

means for operating the spindle from the other side of the lock, substantially as sweet fied.

3. In a lock, the combination of a lock-case with a rotatable guard-plate adapted to be projected over the keyhole, a spindle upon which the guard-plate is mounted and which is adapted to rotate the guard-plate, a key for operating the guard-plate, and a jam-nut on the spindle which is adapted to draw the guard-plate against the lock-case, substan tially as specified.

4. In a lock, the combination of a lock-case with a rotatable guard-plate having a project-ion adapted to engage the keyhole, a spindle upon which the guard-plate is mounted and which is adapted to rotate the guard-plate, a

key for operating the guard-plate, and a 

